GRAND RAPIDS, Mich. (WOOD) — Do we get more snow when it’s 10 degrees outside or when it’s 20 degrees?
Apparently there was a workplace bet placed on this question. When it comes to the answer, this is one of those instances where Michigan is often times an exception, instead of the rule.
Let’s start with the science.
WARM AIR CAN ‘HOLD’ MORE WATER
Of course air can’t “hold” anything. It’s air. However, warm air is much less dense than cold air and has a higher capacity to contain more water vapor than an air mass that is much colder in comparison. For simplicity, we will say that warm air can “hold” more water.
Sometimes it is fun to think of it like a sponge.
Let’s say our cold air mass is trying to scoop up water, but because it is cold, it is a much smaller sponge. That means it can only hold a certain amount of water.
Now let’s say we have a warm air mass. This warm air mass is a much larger sponge. It has the capacity to hold a lot more water.
We all know snow is made of water. So typically if there is warmer air, there is more water in the system, and more snow will fall. Therefore, in most cases, when it is 20 degrees we will see more snow than times when it is 10 degrees.
BUT WAIT, THERE’S MORE…
Lake Michigan is a tricky addition to a winter system. The water temperature of Lake Michigan is usually in the 30s and low 40s throughout winter. When very cold air passes over the lake it can make for some very high snow ratios.
Essentially, any air at 10 degrees that passes over the lake has the opportunity to be filled to the brim with relatively warmer, and more humid air. This instant-saturation can mean a fantastic set up for some excellent snowfall rates of several inches per hour.
Of course, we need to have a few other atmospheric factors at play, too, for these exceptionally high snowfall rates to occur. This means while colder air can create some incredible snowfall amounts, it is never a guarantee. It is often dependent on a “perfect storm” type set up, where the entire atmosphere over an extended period of time is cooperating to give us extensive snow.
IN THE MOUNTAINS, IT IS DIFFERENT TOO
Meteorology is quite complex. I would be remise if I didn’t talk about the soft “pow” that falls in mountainous areas when the air is exceptionally cold.
When air is pushed upslope in a mountain range and is met with incredibly cold conditions, it has a similar effect as Lake Michigan. Incoming air that has a good moisture content at a warmer temperature is forced into a colder environment, providing instant saturation!
If the air is quite cold, this can yield exceptional snowfall rates and ratios, leading to fluffy “dry” snow that can be scooped up driveways and swept off cars with ease. This is how places like the Sierra Nevada Range can receive several feet of snow from a single storm.
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